The elastic properties of conducting vessels in vertebrates are determined, to a major extent, by the ratio of elastin to collagen. Under normal conditions, this ratio is dictated by the need to maintain the elastic modulus in a range that is best able to provide capacitance and pulse smoothing in a pulsatile circulatory system. This elastic modulus can change as a result of aging or disease through the loss of elastin or an increase in collagen. The consequences are a stiffening and dilation of the vessel and loss of its ability to dampen the pulsations in blood flow. Changes in blood flow and pressure result, with hypertension being a biomarker for altered vessel function. This proposal is organized around understanding the relationship between arterial stiffening and blood pressure changes. Aim 1 will take advantage of mice where the elastin/collagen ratio has been reduced by inactivation of one copy of the elastin gene to study the relationship between arterial stiffening and the development of hypertension. Aim 2 will employ conditional and inducible elastin transgenes to change the elastic properties of the vessel wall at different times to investigate the reversibility of stiffness-related hypertension. Aim 3 will utilize gene expression profiling to identify individual genes, gene sets, and molecular pathways that change in response to vessel stiffness and alterations in blood pressure. Aim 4 will pursue several treatment strategies that modulate blood pressure and alter vessel compliance. PUBLIC HEALTH RELEVANCE: This project seeks to elucidate the mechanisms that lead to conduit artery stiffening in the context of hypertension and explore the temporal relationship between arterial stiffening and the development of hypertension in animal models.